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Issues such as global warming, ozone depletion, insufficient landfill capacity, and excess packaging are foremost on the minds of consumers. Companies face a myriad of environmental challenges, but they also recognize the opportunities to be gained by implementing responsible marketing action plans.  相似文献   
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Farley discusses progress US blacks have made in the areas of voting and citizenship rights, residency and housing, and education. A major goal of the civil rights movement was to permit blacks to influence the electoral process in the same manner as whites. Most important in this regard was the Voting Rights Act of 1965; the proportion of southern blacks casting ballots increased sharply since the early 1960s. The Civil Rights Act of 1875 outlawed racial segregation in public accommodations, but by the turn of the century, Jim Crow laws in southern states called for segregation in most public places. Common customs and government policy in the North resulted in similar segregation of blacks from whites. The Montgomery bus boycott and similar protests in dozens of other cities led to enactment of Title II of the Civil Rights Act of 1964, which proscribed such racial practices. By the late 1960s, blacks in all regions could use the same public accommodations as whites. In most metropolitan areas, de facto racial segregation persisted long after the laws were changed. Supreme Court decisions and local open-housing ordinances supported the right of blacks to live where they could afford. However the major change was the Fair Housing Act of 1968, which outlawed racial discrimination in the sale or rental of most housing units. The separation of blacks from whites did not end in the 1970s. Today, in areas which have large black populations, there are many central city neighborhoods and a few in the suburbs which are either all-black or are becoming exclusively black enclaves. Most other neighborhoods have no more than token black populations. Another major effort of civil rights organizations has been the upgrading of housing quality for blacks. By 1980, only 6% of the homes and apartments occupied by blacks lacked complete plumbing facilities (down from 50% in 1940). Unlike the modest changes in residential segregation, racial differences in housing quality have been greatly reduced. By 1960, black students approached parity with whites in terms of measurable aspects of school facilities. In 1940, young blacks averaged about 3 fewer years of educational attainment than whites; the time is nearing when the years of schooling completed by blacks and whites will be the same. In small and medium-sized cities throughout the country, public schools are generally integrated. However, the situation in the largest metropolitan areas is very different. Today, large public schools are segregated, in large part, because blacks and whites live in separate school districts.  相似文献   
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Summary So far, the labour market has not received any special attention from macro-econometric model builders. In this article an attempt has been made to describe the labour market in detail, paying attention to such important phenomena as the friction between labour supply and demand, the heterogeneity of labour, the dependence of labour supply on the labour-market situation, the Phillips mechanism and the impact of real wages on labour demand. To make it suitable for policy simulations, the model has been extended to a complete macro-econometric model, taking account of the fact that both labour and capital limit the production possibilities.This paper summarises an extensive Dutch report on the construction of a model for the Netherlands labour market. The title of the original report is AMO-K: Een arbeidsmarktmodel met twee categorieën arbeid; (AMO-K, A labour-market model with two categories of labour) ; it was published by the Netherlands Economic Institute (NEI) in Rotterdam in the so-called Olive Series, 1982-2, pp. 403ff. Some details of the model presented in that report were changed after its publication; see G. den Broeder, AMO-K 81-12, Tussenrapport betreffende de verdere ontwikkeling van het arbeidsmarktmodel (Interim report on the further development of the labourmarket model), Rotterdam, September 1983. Since then, only minor changes have been carried through. The model reproduced in this paper is the modified version. The model was developed within the National Programme of Labour-Market Research (NPAO) (now defunct), the NPAO organisation having granted a commission to the NEI in Rotterdam.  相似文献   
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The nonlinear Boussinesq equation is used to understand water table fluctuations in various ditch drainage problems. An approximate solution of this equation with a random initial condition and deterministic boundary conditions, recharge rate and aquifer parameters has been developed to predict a transient water table in a ditch-drainage system. The effects of uncertainty in the initial condition on the water table are illustrated with the help of a synthetic example. These results would find applications in ditch-drainage design.Notation A / tanh t - a lower value of the random variable representing the initial water table height at the mid point - a+b Upper value of the random variable representing the initial water table height at the midpoint - B tanh t - C 4/ - h variable water table height - h mean of the variable water table height - h m variable water table height at the mid point - h m mean of the variable water table height at the mid point - K hydraulic conductivity - L half spacing between the ditches - m 0 initial water table height at the mid point - N Uniform rate of recharge - S specific yield - t time of observation - x distance measured from the ditch boundary - (4/SL)(NK)1/2 - (L/4)(N/K)1/2 - dummy integral variable  相似文献   
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